Since the first publication about enzymic interesterification (see e.g. GB 1,577,933) of triglyceride-containing systems in the presence of minimal amounts of water (i.e. amounts of water that are sufficient to activate the enzyme but that are so small that only very limited amounts of hydrolysis products and/or isomerized components derived from these products are formed), many publications have appeared, both in open literature and in patent literature (see e.g. A. R. Macrae, J.A.O.C.S., 60 (2), 1983, pages 291-294; A. R. Macrae, Biocatalysts in Org. Synth., Proc. of Intern. Symp. Noordwijkerhout, Holland, Apr. 1985, pages 195-208; A. J. Russell and A. M. Klibanov, Biochem. Soc. Transactions, Vol. 17 (1989), page 1145; F. X. Malcata c.s., J.A.O.C.S., 67 (12), 1990, pages 890-910; U.S. Pat. No. 4,420,560; JP 62-155048; WO 8802775, including the references cited), which discuss the enzymic modification of edible fats. According to this literature, the interesterification of blends of triglycerides can be carried out, as can the interesterification of blends of oils, with added free fatty acids or esters in order to effect an interchange of the acids originally present in the triglycerides with the added acid. For example, triolein can be enzymically reacted with stearic acid to produce a triglyceride rich in StOSt, which is a major component of cocoa butter. However, in order to produce high conversions of triolein into StOSt, large amounts of expensive stearic acid should be used relative to triolein and the acid by-product produced in the overall process has little volume.
Thus, although the knowledge and understanding of this particular art have greatly improved since the above-mentioned first publication, one main problem still remained, i.e. how to arrive at a process that minimizes the use of expensive acids (or derivatives thereof) and by which high conversion into the desired end products can still be achieved.